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Year |
2001 |
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Question Number |
260 |
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Category |
Select |
Question
What metabolic bone disease is associated with the presence of virus-like inclusion bodies found in the osteoclast?
1- X-linked hypophosphatemic rickets
2- Fanconi’s syndrome
3- Osteopetrosis
4- Osteomalacia
5- Paget’s disease of bone
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Answer (click for answer)
Preferred response: 5
Of the choices given, only Paget’s disease is associated with the presence of virus-like inclusion bodies found in the osteoclasts of those with the disease. These particles most resemble the nucleocapsids of paramyxoviruses, leading to the theory that Paget’s may be a late result of infection from the measles virus, RSV, or canine distemper virus.
Paget’s disease is the second most common metabolic bone disease after osteoporosis, with a prevalence of 3-4% in Europeans and North Americans over the age of 55. It can be monostotic or polyostotic and is characterized by localized enlargement and sclerosis of bone. Most Paget’s patients are asymptomatic. The most common symptom of Paget’s disease is bone pain but joint pain, spinal stenosis causing radiculopathy, and painless bowing deformities are also seen. Treatment for refractory cases is with NSAIDS, calcitonin, or bisphosphonates.
Osteopetrosis, like Paget’s, can be classified as a disease causing an increase in osseous density (osteosclerotic). Also called marble bone disease, this rare condition causes diffuse skeletal hypertrophy with obliteration of marrow spaces. The juvenile form is autosomal recessive and is characterized by severe anemia, hepatosplenomegaly, immune compromise, and often early death. The adult (tarda) form is autosomal dominant and is less severe, although frequent fractures are common.
Osteomalacia is a metabolic disorder is which there is inadequate mineralization of newly formed osteoid. The childhood form is termed rickets. Nonspecific complaints such as weakness and diffuse aches characterize this condition. Radiographs may show Looser’s zones which are radiolucent areas of bones representing areas of microfracture which have healed with the non-mineralized osteoid of osteomalacia. X-linked hypophasphatemic rickets (most common form of rickets) and Fanconi’s syndrome are both conditions caused by renal tubular defects that result in osteomalacia.
Reference: Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 149-165.
Delmas PD, Mennier PJ: The management of Paget’s disease of bone. N Engl J Med 1997;336:558-566.